Sanchez‐Ramos 1994.

Methods	Type of study: randomised double‐blind, placebo‐controlled clinical trial. Method of treatment allocation: women with positive angiotensin test were randomised by means of a computer‐generated list. Calcium and placebo tablets were provided by pharmaceutical company. Stratification: not stated. Placebo: yes, placebo. Sample size calculation: not stated. Intention‐to‐treat analyses: no. Losses to follow‐up: 4 in 67 = 6.0%. Post randomised exclusion: 6 in 67 =  8.9 % did not comply fully with the protocol; 4 were excluded from analysis after randomisation because of a lack of information, 1 was admitted to another hospital (in placebo group), another woman refused to participate after 1 week of trial (in calcium group).
Participants	Location: University of Florida Health Science Center, Jacksonville, Florida. Time frame: January 1, 1989 to July 30, 1993. Eligible criteria: normotensive, nulliparous with increased risk of PIH with positive angiotensin sensitivity test only who were positive roll‐over test (women supine diastolic BP value were more than 20 mmHg higher than those obtained on her side) received angiotensin infusion at 24 to 28 weeks. Exclusion criteria: participants with conditions known to increase the incidence of PIH, including history or evidence of renal disease, collagen vascular disease, diabetes mellitus, chronic hypertension and multiple pregnancy. Total recruited: 281 pregnant women were positive roll‐over test; 67 women positive angiotensin sensitivity test; 33 received calcium, 34 received placebo. Final analyses, calcium group, n = 29, control group, n = 34.
Interventions	2 g of calcium carbonate, compared with placebo (contained starch and were identical to calcium tablets with respected to weight, size, flavour and appearance).
Outcomes	Incidence PIH. Pregnancy outcomes; GA, preterm birth, birthweight, Apgar score, NICU admission, fetal growth restriction, perinatal death.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Women with positive angiotensin test were randomised by means of  a computer‐generated list to receive either 2 g/day of elemental calcium or matching placebo."
Allocation concealment (selection bias)	Low risk	Quote: "Calcium and placebo tablets were provided by pharmaceutical company."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Treatment versus placebo. All participants were blinded to intervention. Placebo contained starch and were identical to calcium tablets with respect to weight, size, flavour and appearance.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The investigators were blinded to treatment. Placebo tablets contained starch and were identical to calcium tablets with respect to weight, size, flavour and appearance.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Six women (8.9%) did not comply fully the protocol; of these, four were excluded from analysis after randomisation because lack of information. One had a single follow‐up prenatal visited and refused to continue participating in the study. She was admitted to another hospital at 35 weeks' gestation with severe preeclampsia and required labour induction (in placebo group). Another woman refused to participate after one week of trial (in calcium group)." Missing data 4 in 67 = 6%.
Selective reporting (reporting bias)	Low risk	None identified.
Other bias	Low risk	None identified.